In recent years, efforts for applying carbon nanotube to electronic devices is actively examined. In order to manufacture such electronic devices, it is necessary to fix carbon nanotube onto a substrate. Typically, processes for obtaining such condition includes a process for fixing the prepared carbon nanotube onto substrate, and a process for adhering metal fine particles that function as a catalyst on a substrate, and allowing a growth of the carbon nanotubes from the metal fine particles.
In these processes, the latter process is beneficial in that a carbon nanotube can be ensured to be disposed at a desired location. When the process for adhering such metal fine particles is adopted, it is required that the metal fine particles should be adhered at desired locations on the substrate with higher controllability. In addition, since the diameter of the formed carbon nanotube is determined by the diameter of the metal fine particles, a critical technical problem would be a reduction in the size of the metal fine particles. More specifically, manufacturing of fine particles having a particle size on the order of the diameter of the carbon nanotube, namely 0.4 nm to several nm, is required, and in particular, a technology for manufacturing fine particles having a minimum size of equal to or less than 1 nm is required.
Patent literature 1 describes a method for providing a pattern of metal fine particles on a substrate. The patent literature describes a technology for aggregating from an aqueous solution containing a metal catalyst ion to form the metal catalyst cluster, by diffusing the aqueous solution containing a metal catalyst ion in a predetermined region on a substrate, and then conducting an annealing process. However, it is difficult to control the size of the fine particles at a level of several nm in this process. Further, it is also difficult to control the quantity of the adhered fine particles.
Meanwhile, dots of a metal can be manufactured on a substrate by employing a fine processing technology for semiconductors. However, the processing dimension is a dot pattern of about 10 nm at minimum, even if the electron beam lithography, which is a fine processing method, is employed, for example. Consequently, the manufacture of a pattern of equal to or less than 10 nm has been conventionally difficult.
On the other hand, a laser ablation process, processes for precipitating metals from a raw material dispersed into a gas phase or a liquid phase or the like have been conventionally employed as a process for manufacturing metal fine particles having a size of equal to or less than 10 nm. Fine particles having particle diameters of equal to or less than 10 nm can be easily obtained by employing these methods. However, it has been difficult to manufacture the metal fine particles at specified locations on the substrate by employing these methods. Consequently, a secondary process for disposing the fine particles on the substrate is required, in addition to the process for manufacturing the fine particles.
[Patent Literature 1]
Japanese Patent Laid-Open No. 2003-168,745